Process of treating a fibrous web



, final use.

Patented Apr. 14, 1942 PROCESS OF TREATING A FIBROUS WEB John M. Behnke, New York, N. Y., assignor to Weycral't Paper Corporation, a corporation of Delaware No Drawing. Application lanuary 17, 1940,

Serial No. 314,294

16 Claims.*

This invention has for its object the production of a material which may be used for .various purposes and particularly as a substitute for textiles such as sheets, pillow cases, table cloths, napkins, window curtains and similar sheet materials which shall possess a high wet and dry strength, softness of texture, flexibility and which shall be absorptive to moisture without being entirely permeable thereto.

More specifically, theinvention has for its object the treatment of a fibrous web, and preferably a waterleaf sheet of paper or other unsized and absorbent paper, in such manner as to produce a material having the characteristics above enumerated and which also shall be'resistant to disintegration when put into service.-

While in some cases it is not entirely necessary, I prefer to first impregnate or saturate the fibres or the web with a dilute aqueous solution of a protein binding agent, such as an aqueous solution of chrome stock glue, hide glue, casein, soya bean protein or egg albumin. The solution preferably is first slightly warmed. In the case of chrome stock glue or hide glue, for example, the solution may be warmed to a temperature of approximately 55 C., the warming being for the purpose of obtaining the viscosity desired. To secure the best results, the solution should contain by weight approximately one part of protein binding agent to nine parts of water.

This preliminary treatment as described provides a foundation for the web and it also pro? vides anchoring means for the ingredients or substances employed in its subsequent treatment. It also makes the web less susceptible to tearing orsplitting during its subsequent treatment and Th glue or other protein binding agent, furthermore, binds the fibres of the web firmly together without any appreciable filling of the interstices therebetween.

After the preliminary treatment of the web just described, it is first thoroughly dried by passing it over paper machinedriers, or otherwise, and it is then treated or impregnated with an aqueous solution of a tannable protein substance, such as chrome stock glue or any of the other protein substances hereinbefore specified, a hygroscopic and water-soluble softening agent or stabilizer, such as glycerine, glycol, sorbitol or other similar water-soluble polyhydric alcohol or catalyst if desired. The solution, if desired, may

first be warmed to a temperature of from 120 Parts by weight Chrome stock glue 1 Glycerine 2.5 to 5.0 Zinc oxide 0.8 to 1 Water, a suflicient amount to make a total of 10 It is of importance that the treating solution should have a pH range value of from 9.2 to 9.8

which relatively is made purposely high in order to control, expedite and facilitate the reaction between the various ingredients of the solution.

-. such as one of caustic soda. If the pH value is in excess of 9.8 however, the glue or other protein ,will suffer substantial deterioration and will be of little or no benefit as decomposition of the glue will result. When this occurs, a distinct odor of ammonia will be detected indicating the break up of the amino groups of the protein. On the other hand, if the pH value is less than 9.2 the desirable adhesive and other characteristics of the glue'will be impaired considerably,

The web preferably is treated or impregnated with the aforesaid solution by passing itthrough a bath thereof while the solution is constantly agitated to cause the insoluble zinc oxide particles to remain in suspension. .When thoroughly impregnated, the web containsdiscrete particles of the zinc oxide throughout both surfaces thereof and obviates tackiness and stickiness of the 'glycerineand glue but chiefly the latter. While I am unable to explain the exact chemical and physical reaction of the zinc oxide with the glycerine and glue I have, found that the presence of the zinc oxide makes the glue coating insolube and horn-like" thereby facilitating and accelerating the drying operation and the web presents a smooth, even surface on both faces thereof. A further reason for theuse of the zinc oxide lies in the fact that it is white in color and also it retains the product in a sweet and hygienic condition and prevents it from becoming sour.

When the web is thoroughly impregnated, as above described, with the composition comprising the tannable protein, plasticizer, and metallic oxide catalyst, said composition not only coats the web on both sides, but fills the interstices thereof, thereby being effectively interlocked therewith. 7

After the above treatment theweb is passed through press rolls to remove the excesses. It is then, and while either in wet or dry condition, subjected to treatment with a solution of a tanning agent, such as formaldehyde or its polymers or other formaldehyde liberating agent. For ex- "ample, a solution of formaldehyde and water may be employed, the strength of which may vary depending on varying conditions and which, by preference, is sprayed on the web although in some cases I may pass the web through a bath of the formaldehyde solution. This latter treatment has the effect of a tanning action. It not only assists in retaining but it enhances the insolubility of the glue and it also acts as a stabilizer in that it prevents deterioration of the glue.

After the formaldehyde treatment, the web may be dried by any known methods although I have found in many cases that .the desirable and superior qualities of the treated web may be enhanced by winding it up in wet condition after the formaldehyde solution treatment and leaving it at room temperature for approximately twelve hours to permit it to "cure itself-after which it may be unwound and dried, preferably mechanically, and then re-wound while subiecting it to the action of wet steam.

By varying the proportions of the ingredients of the aqueous solution of glue, glycerine and metallic oxide a treated fibrous web may be produced which will be found suitable for other uses than for textile substitutes.

The invention claimed is:

1. The method of treating a fibrous web comprising applying an aqueous glue solution thereto and then passing the web through an aqueous solution of glue, glycerine and a water insoluble metallic oxide in suspension.

2. The method of treating a waterleaf paper web comprising impregnating its fibres with a zinc oxide in.

suspension.

3. The method of treating a web of unsized l and absorbent paper comprising impregnating its fibres with a dilute aqueous glue solution, drying the same and then passing it through a solution of glue, glycerine, a water-insoluble metallic oxide and water insubstantially the proportions by weight of glue, 1 part, glycerine, 2.5 to 5.0

parts, metallic oxide, 0.8 to 1 part and water in a sufficient amount to make a total of 10 parts.

4. The-method of treating 'a fibrous web comprising impregnating it with a solution having a pH value of from about 9.2 to about 9.8 and consisting of glue, glycerine, a water-insoluble metallic oxide in suspension and water.

5. The method of treating a.fibrous web comprising passing it through a dilute solution of glue and water, drying the web and then impregnating it with an aqueous solution of glue, glycerine and a water-insoluble metallic oxide in suspension, said solution having a pH range value of from about 9.2 to about 9.8 and finally treating the coated web with a solution of formaldehyde and water. 1

6. The method of treating a fibrous web comprising impregnatingit with an aqueous solution having a pH value of from about 9.2 to about 9.8 and consisting of a glutinous protein, a watersoluble polyhydric alcohol and a water-insoluble metallic oxide insuspension and tanning the web with a suitable tanning agent.

7. The method of treating a fibrous web comprising impregnating it with a solution having a pH value from about 9.2 to about 9.8 and consisting of a glutinous protein, a water-soluble polyhydric alcohol and a water-insoluble metallic oxide and water in the proportions by weight of approximately glutinous protein, 1 part, polyhydric alcohol, 2.5 to 5.0 parts, metallic oxide, 0.8 to 1 part and a suilicient amount of water to make a total of 10 parts and then tanning the web with a solution or formaldehyde and water.

8. The method of treating a waterleaf paperweb comprising saturating the web with a dilute aqueous solution of a glutinous protein, drying the web, treatingit with an aqueous solution of glue, glycerine and zinc oxide while agitating the solution to retain the zinc oxide in suspension and then tanning the coating produced by said second named solution with a solution of formaldehyde and water.

9. The method of treating a fibrous web comprising impregnating its fibres with an aqueous solution of a protein binding agent, drying the web, impregnating it with an aqueous solution of a tannable protein, a plasticizer and a waterinsoluble metallic oxide while agitating the solution to retain the metallic oxide in suspension and then tanning the web with a suitable tanning agent.

10. The method of treating a fibrous web comprising impregnating its fibres with an aqueous solution of a glutinous protein, drying the web, impregnating it with an aqueous solution of a glutinous protein, a softening agent and a waterinsoluble metallic oxide while agitating the solution to retain the metallic oxide in suspension,

tanning the web with a suitable tanning agent,

winding up the web in wet condition after the tanning operation, and then drying the same.

11. The method of treating a web of waterleaf paper comprising impregnating its fibres with an aqueous dilute solution of glue, drying the web,

impregnating it with an aqueous solution of glue, glycerine and zinc oxide while agitating the solution to retain the zince oxide in suspension, treating the web with an aqueous formaldehyde solution, winding up the web in wet condition and then unwinding it and drying. it after several hours and finally re-winding it while subjecting it to the action of wet steam.

12. The method of treating a fibrous web comprising impregnating its fibres with an aqueous solution of a protein binding agent and subsequentlyimpregnating it with an aqueous solution of a tannable protein, a plasticizer, and a water-insoluble metallic oxide, the last-mentioned solution having a pH within the range of about 9.2 to about 9.8.

13. The method of treating a fibrous web com,- prising applying thereto an adhesive binding agent to bind the fibres together while retaining the porosity of the web and subsequently treating the web to fill the interstices thereof with a solution consisting of a tannable protein, a plasticizing agent, and a metallic oxide selected from the group consisting of zinc oxide and lead oxide, said solution having a pH within the range of about 9.2 to about 9.8.

. 14. The method of treating a fibrous web comconsisting of a tannable protein, a pla'sticizing apent and a water-insoluble metallic oxide in suspension, and tanning-the web'with a suitable tanning agent.

15. The method of treating a fibrous web com? prising impregnating it with a solution having a pH value of from about 9.2 to about 9.8 and ina'avopio i l 3 eluding a tannable protein, a jalasticizer and a water-insoluble metallic oxide in suspension in the solution.

- 16. The method of treating a fibrous web comprising impregnating its fibres with an aqueous solution of a glutinous protein, drying it, and then impregnating it with an aqueous solution of a glutinous proteim a plasticizer and a waterinsoluble metallic oxide in suspension.

' 30m; M. BEHNKE. 

